So I think I understand this correctly, but I just want to make sure.

Say I am zeroing my scope.  The scope is mil/mil with 1/10th mil clicks. I shoot a group at 600 yards, and when I go check out the target, my group is, let's say, 14" low. Is the following required math to roughly determine the adjustment necessary correct?

1)  determine that a full mil at 600 is worth 3.6 x 6= 21.6"
2)  divide the required change (14") by the mil value (21.6), which gives me .648
3)  .648 would be the correction in full mils, which could be rounded to .6 or .7 in tenths of a mil, which means 6 or 7 clicks.

Am I on the right track?

Thank you

Not quite. First, abandon yards. Time to work in meters so you can get full benefit of a base 10 system.

Don't get me wrong, your math is right. You're just making things harder by not going metric.

.1mrad = 1cm @ 100m
600 yards in meters is 548m.
14 inches in centimeters is 35.56cm
Now move the decimal points to make both in meters
.355 / 548 = .00064 so 6 clicks

Zeroing at 600 yards is possibly the right thing for you but generally I advise against it for almost all situations outside of actually sniping in combat. You can also use your reticle to figure out how far to adjust without leaving the rifle, assuming that you have an MRAD reticle. It's easier to do at 100yrds than 600 which is another good reason to move your zero closer if you can possibly deal with that.

you're exactly correct.   do not switch to meters either, unless you are planning to shoot with people who also use meters (like some units in the military, or people in the 2nd and 3rd worlds)

most ranges you visit in the US will be laid out in yards.  any NRA match you attend will have distances in yards.  e.g. HP is 200, 300, 600 yards across the course.  Palma is 800, 900, 1000 yards.  not meters.
Any PRS style match you go to will have target distances given in yards.   if you work in meters, you will only give yourself more math to do, and it's just as easy to do in yards anyways.  (you did in 3 steps what took 4 to do in meters)

Thank you all.

The 600 yards was just a theoretical example.  This is for 3 gun, so I'm not ranging anything with the scope--it's all done before hand with a range finder.  The question was just more so I could understand what I was doing when I was zeroing my scope, as I'm new to the mil system.

Thank you all for your help.

If your scope is first focal plane, just use the scope reticle to measure the distance between the point of aim and point of impact.  

This  However, I'm going to amend that with you don't need a FFP scope to do this.  Just make sure you are on the correct magnification for your reticle to read mils properly.

Indeed. Mils are not the metric system.

s = r * theta, when theta is in radians. How do it work?

I do like this, 0.360 in x 6.00=  2.16 in per click. 14.0in / 2.14 in/click=6.48 clicks, I then put the in/click on the range card for each 100 yd increment for easy reference.

I too shoot in freedom units.

Your math is  correct and that correction is so close to the middle of the adjustment that it doesn't matter which one you go with. At that distance .1mil is 2.16" and your rifle is probably only capable of shooting a 6" grouping.

FWIW the first time I shot an informal match with my rifle my 2 spotters were low and to the right and right next to each other.

I just treated it like an artillery adjustment.

I put the horizontal crosshair on the center of the 2 shot group and moved it over until the vertical crosshair bisected the X in the X-ring. It was EXACTLY 2 mildots up so I went up 2 mils, IE 20 .1 clicks.

Then I put the vertical crosshair on the center of the 2 shot group and raised the rifle until the horizontal crosshair bisected the X and it was a whisker over 1.2way between the center and the first mildot. I moved the scope 6 each .1 mil clicks.

First shot for score?

X and so were the next three! I think I had one flyer (caused by me) into the 9 ring and wound up with a 99-5X.(IIRC)

I keep wondering why scope makes put mildot reticles and MOA adjustments on mildot scopes. It's like buying a Toyota and an SAE wrench set to maintain it.

Actually I figure they do that for the Rambo wannabes that simply either are too ignorant to know*, are too lazy to learn or are just plain stupid.

It's a wonderful system. All you have to do is learn to use it and get that MOA mentality out of your head for a minute.



* Duh! Dis is cool! It's got mildot! The army uses it so it must make my rusty old rummage sale rifle look cool. Hey1 WTF is this .1 mil click shit? I want mine in MOAs like it's 'sposed ta be.

I've said this before in another thread, and it seemed to turn a light on for a few people.  

1 Mil is 1 unit at 1000 units, it doesn't matter if that is inches, feet, furlongs or fathoms (but how do it know?).  

so if you're 1000 yards away, 1 Mil is 1 yard.  then at 500 yards, 1 Mil is 1/2 a yard, or 18 inches.  If you can see impacts on your target through the scope, and have a mil reticle, you can make adjustments based on the reticle as long as you're at the correct magnification or you're using a FFP scope.  another way to do your math on how many inches a Mil is at a certain yardage is to take the fraction of 1000 yards your target is at, times 36.  

so for your example,
.6 x 36 = 21.6", then you can divide your correction into it, 14"/21.6" = .648 Mil.  

if you have a mil reticle at the correct magnification or FFP, again you can estimate range of a known size target, for example the ribcage on an average doe is around 18", so if the body of the deer is 2 mils, the deer is 250yards away.  estimating size of unknown target at known distance is same as the calculation above, measure with reticle in Mils, multiply distance fraction by 36, times number of mils the target is.

Correct or you could say .36(one click) x 6 = 2.16......... then 14/2.16 =6.49 clicks..... same thing. somebody covered already

If you are at 647 yards then just use 6.47 as the multiplier.

This is correct but it will be less precise depending on how well you can do it. Actually taking the target and measuring it and doing the calculation will be exact.

Just estimate .1 mils as 1/3 MOA. Do MOA math. Close enough.

bump

Spotting scope is FFP MIL reticle as well so correction will be in mils or relative to the target.

1mil left .5 up

2.5 right 1 mil up

relative to target:

hold left shoulder

hold belt

hold .2 off right shoulder

Hold left hip

Thank you all for the advice--I really appreciate it.

I won't be using the scope for ranging or anything--it's 3-gun, so no spotters or anything.

bump because its a great thread

That is the simplest breakdown of mils I've ever read. Thanks!

This. I just measure with the mil reticle and dial the difference.  Super easy.

Best advice I can give is to shoot known distances and make your own drop tables.   Then practice both using the reticle to use those drop charts.  Also practice knob turning for center crosshair hold on target.  Do this when you have time to set up a shot which likely doesn’t apply in three gun.  

Then there is the hybrid of the two, dial turn for the elevation drop but hold off on the main horizontal cross for wind using your mil markings/dots.   That is probably the best for switching winds as you can do that super fast if you see the change and don’t lose track of what wind you dialed on the scope. ( or stupidly dial it in the opposite direction)

Your math came up with the right answer

Another approach would be :

At 600 yards,   O.1 mil = 6 x 0.36 = 2.16 inches

14 in / 2.16 in = 6.48 mil

Almost there. It would be 6.48 10ths. So you have to divide by 10 still, or just carry the decimal to make it .648mils of adjustment, or 6.48clicks.